This is a great article on First Light's tritium production: https://nickhawker.com/2023/01/22/the-nuclear-physics-of-why...

Summing up: you need your fusion neutrons to breed more tritium from lithium. Lithium-7 produces tritium plus a lower-energy neutron that can breed one more tritium. Lithium-6 produces tritium but without the extra neutron.

Most designs lose a lot of neutrons, so they have to either enrich lithium for more lithium-7, or (most commonly) mix in either lead or beryllium as a neutron multiplier.

First Light's design captures 99% of the neutrons, so they think they can breed 50% more tritium than they consume with just natural lithium.

> Although the machine itself will not generate power, it will be used to develop technology needed for future inertial confinement fusion energy powerplants.

5 years away and it will not even generate power. Seems a risky bet.

I'm sympathetic, but how is projectile implosion supposed to be "proven" like NIF was? If anything, corrections to the imperfections which will come about and lead to instabilities will be harder with actually physically driven projectiles unlike the lasers at NIF where it's light and they can do crazy things like cross-beam energy transfer.

I also don't know why they claim to be "proven" by NIF's result, they are "ICF" by a choice of definition but it's a very different physical system, and just like NIF took decades, ironing out their sources of instabilities will literally be most of their effort, which they'll only know once they've done actual experimental runs.

Helion seems to be the only Fusion startup that is confident of net energy gain at a system level within the next few years. If they can pull of Fusion Reaction direct to Electricity ie eliminating steam generator stage would be a game changer - but seems too good to be true. Sam Altman believes in it, he put in $375M of his own money.

I am highly skeptical of First Light Fusion. While the general branch of fusion reasearch (impact fusion) was widely studied decades ago, the issue was creating the immense speeds necessary for ignition - you need to get the projectile up to ~.1% of the speed of light. While this is probably physically possible, doing it repeatably and economically was deemed impractical.

First Light is attempting fusion with a much lower velocity projectile, too low to work based on the previous research, but it's okay because they have a magical amplifier at the end that makes up the difference. They have not disclosed the design of this amplifier, nor have they published any peer reviewed material detailing the tests they claim validate that the amplifier works. So from a strictly scientific perspective, that's a big red flag.

On the economics side, the main, and really only selling point of impact fusion was the simplicity - where all other ICF fusion concepts suffer from instabilities and thus need incredible levels of engineering precision to get right, with impact fusion you're just brute forcing a solution by slamming the fuel together so hard that it can't do anything but fuse. As long as you have the right mass moving at the right speed, you're good. The energy amplifier completely negates this though. Now you need an ultra-precision manufactured part hit in just the right way to properly focus the energy, and all the instabilities of ICF come roaring right back. If your goal is just understanding the physics, like at the NIF, that's not a huge issue. If your goal is to produce a powerplant that can compete commercially with existing options then that's a second major red flag.

Finally, there is the company itself. If you look at the team, the CEO has a little bit of plasma physics experience, but pretty much everyone else is a businessman who advertises their expertise in rapid growth and large exits for startups. This is the team I'd want if my goal was to build a lot of hype and bring in a lot of gullible investor money; it's not the team I'd want if my goal were accomplishing a feat of science and engineering that generations of geniuses and well backed programs have repeatedly tried and failed to achieve. Maybe the founder had a true eureka moment, discovered something no one else had ever considered, and these are just the type of risktakers who are willing to take the leap of faith necessary to turn the idea into reality, but to a cynical person like me it's a red flag.

But hey, it would be really cool if they proved me wrong.

I think there’s a lot of promise in FLF’s designs (especially for in-space fusion propulsion), but they’re moving too slowly.